In manufacturing or assembling electronic parts such as semiconductor chips, if static electricity is generated in the electronic parts or jigs for manufacturing and assembling the same, it is not possible to smoothly manufacture or assemble the electronic parts. Thus, an ion generating apparatus also called an ionizer or ion generator is used to blow air which has been subjected to ionization, i.e., ionized air to members requiring removal of electrostatic charge. The members which require electrostatic charge removal, namely, removal of static electricity include a pipe for guiding air or liquid and an operating portion in a machine such as a robot or parts feeder, in addition to the aforementioned electronic parts. The ionized air is supplied to surfaces of such members, whereby electrostatic charge thereon is neutralized.
The ion generating apparatus used in such applications has a blow type, in which the ionized air is guided to a predetermined place requiring removal of electrostatic charge through a tube or pipe, and a fan type in which the ionized air is blown from a blowing port using a fan. The blow type ion generating apparatus has a head made of a conductor and having a through hole for guiding air therein, and a discharge electrode made of a conductor and disposed inside the through hole, wherein an insulating member is attached to an inner face of the through hole. A fitting is attached to the head, and the ionized air is supplied to a predetermined charged place through a hose or pipe or the like connected to the head via the fitting. On the other hand, the fun type ion generating apparatus has a duct for forming an air guide passage, and a discharge electrode disposed inside the duct, wherein the ionized air is guided through the duct to the predetermined charged place.
Regardless of the above types, a basic structure for generating ions is such that several kV or more AC voltage (or pulsed DC voltage) is applied to the discharge electrode to produce a corona discharge, whereby air flowing in an air flow passage is ionized by an electric field of the corona discharge.
However, in order to generate a large amount of ionized air, an increase of a flow rate of air in the air flow passage becomes necessary, whereby the pressure or flow rate in the air flow passage is increased, which results in any fear of making the corona discharge around the discharge electrode unstable. As described above, when the corona discharge becomes unstable, a ratio of positive ions to negative ions, that is, an ion balance is easily biased also in the ionized air generated and thus there is the problem that electrostatic charge removal performance or the like is reduced.
An object of the present invention is to provide an ion generating apparatus capable of stabilizing an ion balance even in generating a large amount of ionized air.